In some South Dakota counties, people repeatedly arrested for drunken driving can continue to drive, but they must report to their local sheriff for breath testing twice a day ? every morning and every night.

If they don't show, they're tracked down and thrown in jail. And if they fail the test ? if they have been drinking anything at all ? they go to jail on the spot.

It's a two-year pilot program that has worked so well that South Dakota is about to become the first state to put the approach into law. A bill to take the 24/7 Sobriety Program statewide unanimously won final approval in the Legislature on Tuesday.

South Dakota Attorney General Larry Long, who started the experiment, noted that many people arrested for DUI are alcoholics who do it again and again, even after their licenses have been taken away. So the way to attack the problem, he said, is not to prevent them from getting behind the wheel but to stop them from drinking.

"If they quit drinking, I don't care if they drive," he said.

Authorities have no figures that could show whether the pilot program in 14 of South Dakota's 66 counties has saved lives or reduced drunken driving arrests or crashes. But it appears to be keeping people sober.

More than 1,000 chronic drunken drivers ? people who had been arrested at least twice for being intoxicated behind the wheel ? were put into the program, and they passed more than 99 percent of the 166,000 breath tests at sheriffs' offices, Long said.

Lacey Graff, 24, a legal secretary in Sioux Falls, went into the program in August after being arrested a third time for drunken driving, and is serving 90 days behind bars for her last offense.

While awaiting sentencing, she was tested twice a day and failed twice, spending a night behind bars each time. But she said the experience led her to check into rehab.

"It's a pain in the neck to have to go down there twice a day," she said. But she added: "It may have saved my life, with the path I was going. I'd been continuing on that road for almost two years, being drunk almost every day."

South Dakota has one of the nation's highest alcohol-related highway fatality rates. Twenty-six percent of drivers in deadly crashes were drinking in 2005, the latest figures available.

The problem is blamed, in part, on heavy drinking in South Dakota, and the big, sparsely populated expanses that make it necessary to drive to get just about anywhere.

States deal with repeat drunken drivers in a variety of ways, including taking away their licenses or plates, impounding their cars and installing ignition devices that prevent vehicles from starting if the operators have alcohol on their breath.

Long tried out twice-a-day testing decades ago as a local prosecutor in a rural county and liked the results.

"These are people who have chronic alcoholism problems. We're keeping them sober," he said.

People checking in twice daily with sheriffs pay $2 a day for the alcohol testing. Most of them are in the program for about four months.

Hughes County Sheriff Mike Leidholt is sold on the program. He said about 40 people come in twice daily for breath tests at the jail.

"It is effective. It does work," Leidholt said. "If they blow a hot test, they're immediately taken to jail."

A bill to provide $345,000 in state money to help take the program statewide cleared the Legislature without a single negative vote, either on the floor or in committee. Republican Gov. Mike Rounds plans to sign it within days.

Legislators were clearly impressed with the results.

"It takes the drink away from the driver," said Republican state Rep. Mike Vehle.